U.S. patent application number 16/317738 was filed with the patent office on 2020-02-06 for high-power microwave borehole fracturing device for engineering rock mass.
The applicant listed for this patent is NORTHEASTERN UNIVERSITY. Invention is credited to Xiating FENG, Yanhua GONG, Yuanhui LI, Gaoming LU, Tianyang TONG, Jianhua WEN, Xiwei ZHANG.
Application Number | 20200040717 16/317738 |
Document ID | / |
Family ID | 63215544 |
Filed Date | 2020-02-06 |
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United States Patent
Application |
20200040717 |
Kind Code |
A1 |
FENG; Xiating ; et
al. |
February 6, 2020 |
HIGH-POWER MICROWAVE BOREHOLE FRACTURING DEVICE FOR ENGINEERING
ROCK MASS
Abstract
A high-power microwave borehole fracturing device for an
engineering rock mass includes a high-power microwave generator, a
high-power microwave coaxial heater, a high-power low-loss
microwave coaxial transmission line, and a microwave power adaptive
regulation and control system. The high-power microwave generator
includes a continuous wave magnetron, a permanent magnet, a
waveguide excitation chamber, a coaxial circulator, a coaxial
matching load, a coaxial coupling converter, a waveguide coaxial
converter, and an output waveguide. The high-power microwave
coaxial heater includes a microwave transmission inner conductor, a
microwave transmission outer conductor, a microwave input
connector, a microwave short circuit cap, and a conductor
supporting cylinder. The high-power low-loss microwave coaxial
transmission line includes an input end coaxial line, middle
section coaxial lines, and an output end coaxial line. The
microwave power adaptive regulation and control system includes an
impedance matching regulator, a microwave power controller, and a
temperature sensor.
Inventors: |
FENG; Xiating; (Shenyang
City, CN) ; LU; Gaoming; (Shenyang City, CN) ;
LI; Yuanhui; (Shenyang City, CN) ; ZHANG; Xiwei;
(Shenyang City, CN) ; WEN; Jianhua; (Shenyang
City, CN) ; TONG; Tianyang; (Shenyang City, CN)
; GONG; Yanhua; (Shenyang City, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NORTHEASTERN UNIVERSITY |
SHENYANG CITY |
|
CN |
|
|
Family ID: |
63215544 |
Appl. No.: |
16/317738 |
Filed: |
May 16, 2018 |
PCT Filed: |
May 16, 2018 |
PCT NO: |
PCT/CN2018/087141 |
371 Date: |
January 14, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/26 20130101;
E21B 36/04 20130101; E21B 43/285 20130101 |
International
Class: |
E21B 43/26 20060101
E21B043/26; E21B 43/285 20060101 E21B043/285; E21B 36/04 20060101
E21B036/04 |
Claims
1. A high-power microwave borehole fracturing device for an
engineering rock mass, comprising a high-power microwave generator,
a high-power microwave coaxial heater, a high-power low-loss
microwave coaxial transmission line, and a microwave power adaptive
regulation and control system; wherein the high-power microwave
generator is connected with the high-power microwave coaxial heater
through the microwave power adaptive regulation and control system
and the high-power low-loss microwave coaxial transmission line
sequentially; the high-power microwave coaxial heater is used for
radiating microwave energy to cause fracturing of rocks around a
borehole of the engineering rock mass; the microwave power adaptive
regulation and control system is used for performing real-time
impedance matching of a microwave power outputted by the high-power
microwave generator; and the high-power low-loss microwave coaxial
transmission line is used for transmitting impedance-matched
microwaves into the high-power microwave coaxial heater.
2. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 1, wherein the high-power
microwave generator comprises a continuous wave magnetron, a
permanent magnet, a waveguide excitation chamber, a coaxial
circulator, a coaxial matching load, a coaxial coupling converter,
a waveguide coaxial converter, and an output waveguide; wherein the
permanent magnet is a circular ring structure, and the permanent
magnet is fixedly sleeved around an outer side of the continuous
wave magnetron to provide a magnetic field for the continuous wave
magnetron; the continuous wave magnetron is connected with a power
supply through a wire, a microwave emitting head of the continuous
wave magnetron is located in the waveguide excitation chamber, DC
electrical energy is converted into microwave energy by the
continuous wave magnetron, the microwave energy generated by the
continuous wave magnetron enters the waveguide excitation chamber
through the microwave emitting head, and a guided mode is formed in
the waveguide excitation chamber; three end openings are formed in
the coaxial circulator, and defined as a first end opening, a
second end opening and a third end opening respectively; the
waveguide excitation chamber is connected with the first end
opening of the coaxial circulator through the coaxial coupling
converter, and the microwave energy generated by the continuous
wave magnetron enters the coaxial circulator after passing through
the waveguide excitation chamber and the coaxial coupling converter
sequentially; the output waveguide is connected with the second end
opening of the coaxial circulator through the waveguide coaxial
converter, the microwave energy in the coaxial circulator enters
the output waveguide through the waveguide coaxial converter, and
the microwave energy is converted from a coaxial output mode to a
waveguide mode; the output waveguide is a microwave output portion
of the high-power microwave generator; and the coaxial matching
load is connected to the third end opening of the coaxial
circulator, and the coaxial matching load is used for absorbing
microwave reflected power isolated by the coaxial circulator and
protecting the coaxial circulator and the continuous wave
magnetron.
3. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 1, wherein the high-power
microwave coaxial heater comprises a microwave transmission inner
conductor, a microwave transmission outer conductor, a microwave
input connector, a microwave short circuit cap, and a conductor
supporting cylinder; wherein the microwave transmission inner
conductor is a solid cylinder structure or a hollow cylinder
structure, the microwave transmission outer conductor is a
cylindrical structure, the microwave transmission outer conductor
is coaxially sleeved around an outer side of the microwave
transmission inner conductor, and the microwave transmission inner
conductor and the microwave transmission outer conductor which are
arranged in a coaxial sleeving state are fixedly mounted between
the microwave input connector and the microwave short circuit cap;
an annular space is formed among the microwave transmission inner
conductor, the microwave transmission outer conductor, the
microwave input connector and the microwave short circuit cap, and
the annular space is stuffed by the conductor supporting cylinder
which maintains a coaxial state between the microwave transmission
inner conductor and the microwave transmission outer conductor; and
a plurality of microwave radiating openings for radiating microwave
energy outwards are formed in a cylinder wall of the microwave
transmission outer conductor, and an anti-breakdown dielectric
block is stuffed in each of the microwave radiating openings.
4. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 23, wherein the conductor
supporting cylinder and the anti-breakdown dielectric blocks are
both made of a wave-transmitting material; the microwave
transmission inner conductor, the microwave transmission outer
conductor, the microwave input connector and the microwave short
circuit cap are all made of a conductive metal material; each of
the microwave radiating openings is in the shape of a curved slit,
and a length of the curved slit of the microwave radiating opening
is equal to 2/3 of a circumference of the microwave transmission
outer conductor; the anti-breakdown dielectric blocks are exactly
the same as the microwave radiating openings in shape and size, the
microwave radiating openings are distributed in an axial direction
of the microwave transmission outer conductor in an equidistant
manner, and the adjacent microwave radiating openings face
oppositely; a distance between the adjacent microwave radiating
openings is 1/ {square root over (.epsilon.)}.sub.r, wherein
.epsilon..sub.r is a relative dielectric constant of the
wave-transmitting material; and a distance between the microwave
radiating opening adjacent to the microwave short circuit cap and
the microwave short circuit cap is 1/2.lamda..sub.p, wherein
.lamda..sub.p=.lamda. {square root over (.epsilon..sub.r)}; wherein
.lamda..sub.p is a phase wavelength, .lamda. is a microwave
wavelength, and .epsilon..sub.r is the relative dielectric constant
of the wave-transmitting material.
5. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 1, wherein the high-power
low-loss microwave coaxial transmission line is a combined
structure, and comprises an input end coaxial line, middle section
coaxial lines, and an output end coaxial line, wherein the input
end coaxial line is connected with the output end coaxial line
through a plurality of middle section coaxial lines connected in
series; the input end coaxial line comprises an input end inner
conductor, an input end outer conductor, an input end microwave
input connector, an input end microwave output connector, and an
input end conductor supporting disk; wherein the input end inner
conductor is a solid cylinder structure or a hollow cylinder
structure, the input end outer conductor is a cylindrical
structure, and the input end outer conductor is coaxially sleeved
around an outer side of the input end inner conductor; the input
end microwave input connector is coaxially and fixedly connected to
a front end aperture of the input end outer conductor, the input
end conductor supporting disk is fixedly mounted between the input
end inner conductor and the input end microwave input connector,
and a coaxial state between the input end inner conductor and the
input end outer conductor is maintained through the input end
conductor supporting disk; and the input end microwave output
connector is coaxially and fixedly connected to a rear end aperture
of the input end outer conductor.
6. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 5, wherein each of the
middle section coaxial lines comprises a middle section inner
conductor, a middle section outer conductor, a middle section
microwave input connector, a middle section microwave output
connector, and a middle section conductor supporting disk; wherein
the middle section inner conductor is a solid cylinder structure or
a hollow cylinder structure, the middle section outer conductor is
a cylindrical structure, and the middle section outer conductor is
coaxially sleeved around an outer side of the middle section inner
conductor; the middle section microwave input connector is
coaxially and fixedly connected to a front end aperture of the
middle section outer conductor, the middle section conductor
supporting disk is fixedly mounted between the middle section inner
conductor and the middle section microwave input connector, and a
coaxial state between the middle section inner conductor and the
middle section outer conductor is maintained through the middle
section conductor supporting disk; the middle section microwave
output connector is coaxially and fixedly connected to a rear end
aperture of the middle section outer conductor; and the middle
section microwave input connector and the input end microwave
output connector are in coaxial threaded connection and matching,
or the middle section microwave input connector and the middle
section microwave output connector of the adjacent middle section
coaxial line are in coaxial threaded connection and matching.
7. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 6, wherein the output end
coaxial line comprises an output end inner conductor, an output end
outer conductor, an output end microwave input connector, an output
end microwave output connector, an output end front conductor
supporting disk, and an output end rear conductor supporting disk;
wherein the output end inner conductor is a solid cylinder
structure or a hollow cylinder structure, the output end outer
conductor is a cylindrical structure, and the output end outer
conductor is coaxially sleeved around an outer side of the output
end inner conductor; the output end microwave input connector is
coaxially and fixedly connected to a front end aperture of the
output end outer conductor, and the output end front conductor
supporting disk is fixedly mounted between the output end inner
conductor and the output end microwave input connector; the output
end microwave output connector is coaxially and fixedly connected
to a rear end aperture of the output end outer conductor, and the
output end rear conductor supporting disk is fixedly mounted
between the output end inner conductor and the output end microwave
output connector, and a coaxial state between the output end inner
conductor and the output end outer conductor is maintained by the
output end front conductor supporting disk and the output end rear
conductor supporting disk; and the output end microwave input
connector and the middle section microwave output connector are in
coaxial threaded connection and matching.
8. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 7, wherein a dry cooling
air inlet is formed in the input end microwave input connector, a
plurality of dry cooling air through holes are formed in the middle
section conductor supporting disk and the output end front
conductor supporting disk, and a plurality of dry cooling air
exhaust holes are formed in the output end microwave output
connector.
9. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 7, wherein the input end
inner conductor, the input end outer conductor, the input end
microwave input connector, the input end microwave output
connector, the middle section inner conductor, the middle section
outer conductor, the middle section microwave input connector, the
middle section microwave output connector, the output end inner
conductor, the output end outer conductor, the output end microwave
input connector, and the output end microwave output connector are
all made of a conductive metal material; and the input end
conductor supporting disk, the middle section conductor supporting
disk, the output end front conductor supporting disk, and the
output end rear conductor supporting disk are all made of a
wave-transmitting material.
10. The high-power microwave borehole fracturing device for an
engineering rock mass according to claim 1, wherein the microwave
power adaptive regulation and control system comprises an impedance
matching regulator, a microwave power controller, and a temperature
sensor; wherein one end of the impedance matching regulator is used
for receiving the microwaves outputted by the high-power microwave
generator, and the microwave incident power is recorded in the
impedance matching regulator; the other end of the impedance
matching regulator is used for outputting microwaves; the
microwaves outputted by the impedance matching regulator are
transmitted to the high-power microwave coaxial heater through the
high-power low-loss microwave coaxial transmission line, and then
the rock mass is fractured by the microwaves radiated from the
high-power microwave coaxial heater; after the microwaves reflected
by the rock mass return to the impedance matching regulator after
passing through the high-power microwave coaxial heater and the
high-power low-loss microwave coaxial transmission line
sequentially, the microwave reflected power is recorded by the
impedance matching regulator; the microwave power controller is
used for receiving the microwave incident power and the microwave
reflected power fed back by the impedance matching regulator; the
temperature sensor is used for collecting temperature data of the
rock mass during microwave fracturing, and the temperature data is
directly fed back to the microwave power controller; reflection
coefficient data of the rock mass is pre-set in the microwave power
controller; the microwave power controller firstly takes the
microwave incident power and the microwave reflected power fed back
by the impedance matching regulator as the basis, and then
calculates microwave power data satisfying impedance matching
through the temperature data and the reflection coefficient data;
and the microwave power controller finally feeds back the microwave
power data satisfying impedance matching to the impedance matching
regulator, and finally the real-time impedance matching is
performed on the microwave power outputted by the high-power
microwave generator through the impedance matching regulator.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates generally to a borehole
fracturing device, and more particularly, to provide a high-power
microwave borehole fracturing device for an engineering rock
mass.
2. The Prior Arts
[0002] A microwave-assisted rock fracturing technology is a new
rock fracturing technology which has great potential. Before being
cut by a mechanical tool, a rock is radiated and fractured by
microwaves in advance, so that the mechanical properties, such as
uniaxial compression, tensile strength and point load strength, of
the rock can be reduced. The problem that the mechanical tool is
easy to wear out when a hard rock is fractured with a mechanical
method is solved, the rock fracturing efficiency can be improved,
and the rock fracturing cost can also be reduced. Through the
adoption of the microwave-assisted fracturing technology, the
stress of a deep rock mass can be effectively released. The
pre-fracturing of the rock mass is additionally provided on the
basis of a stress release hole, so that a fracture zone is formed
in the surrounding rock, the stress and the energy concentration
level of the internal rock mass can be reduced, and therefore the
risk of extremely strong rock burst can be effectively reduced.
[0003] In order to apply the microwave-assisted rock fracturing
technology to the engineering rock mass for borehole fracturing,
high-power microwaves need to be used for fracturing. Therefore, a
high-power microwave fracturing device needs to be used, and a
suitable microwave heater and a suitable microwave coaxial
transmission line are also needed.
[0004] However, at present, most of conventional microwave
generators use a box-type structure with a single-mode or
multi-mode resonant chamber. The microwaves are reflected in the
closed chamber, so that the rock in the chamber can absorb the
microwaves. The frequency of the microwaves is 915 MHz or 2450 MHz,
and the maximum power outputted by the microwaves is about 30 kW.
Such type of microwave generators are only suitable for indoor
tests and can be used for studying the influence of microwave
radiation on the thermal physical properties and mechanical
properties of the rock, but cannot meet the practical engineering
application requirements. Although the 30 kW microwave power can
meet the fracturing need of small-sized rock blocks, for the
engineering rock mass in practical engineering, such microwave
power is still too small. After the microwaves with such power are
radiated to the engineering rock mass, the rate of temperature rise
of the engineering rock mass is low, so that partial melting of the
engineering rock mass can be caused, and the desired fracturing
effect cannot be produced. Can stacking manner of multiple groups
of small power be applicable? The answer is No. Because when a
plurality of microwave heaters are stacked for heating, the
microwave energy radiated by the microwave heaters is coupled or
offset with each other before being absorbed by the engineering
rock mass, and therefore rock fracturing cannot be achieved. In
addition, some microwave generators that can meet high-power output
requirements are industrial microwave generators being large in
size, a magnetic field is provided through an electromagnet, and
reflected power is isolated by using a Y-junction circulator. Such
a microwave generator neither can be moved to the project site for
application, nor can be combined with rock fracturing
machinery.
[0005] At present, the conventional microwave heaters cannot meet
the high-power borehole fracturing requirements due to low power
capacity and small microwave radiation range. If high-power
microwaves are forcibly input into the conventional microwave
heaters, air ionization and breakdown sparking can be caused, so
that the high-power microwave fracturing device is damaged.
[0006] At present, the structure of the conventional microwave
coaxial transmission line cannot meet the high-power borehole
fracturing requirements due to low power capacity and high
microwave energy loss during remote transmission. In addition, an
outer diameter dimension of the microwave coaxial transmission line
cannot effectively meet the dimension requirement of the rock mass
borehole, and on-site assembly and disassembly are
inconvenient.
[0007] Further, the current technical scheme for fracturing the
engineering rock mass by using microwaves mainly stays in the
indoor test stage, and the microwave power outputted by the
microwave generator acts on a rock sample in a constant state.
However, since the temperature of the rock sample changes greatly,
the microwave characteristics (dielectric constant, dielectric
loss, and the like) of the rock sample can change greatly too, and
finally, the load impedance of the rock sample can have dynamic
characteristics. That is to say, when the load impedance of the
rock sample changes dynamically, if the constant microwave power
still acts on the rock sample, impedance mismatch can occur
inevitably. The direct consequence is that the microwave reflected
power increases, so that not only is the stability of microwave
equipment reduced, but also the utilization efficiency of the
microwave energy is reduced. Therefore, in order to successfully
apply the microwave-assisted rock fracturing technology to
practical engineering, the adaptive regulation and control of
microwave power must be achieved, so that the real-time matching of
impedance can be met when the load impedance of the rock changes
dynamically.
SUMMARY OF THE INVENTION
[0008] A primary objective of the present invention is to provide a
high-power microwave borehole fracturing device for an engineering
rock mass, in which a high-power microwave generator, a high-power
microwave coaxial heater, a high-power low-loss microwave coaxial
transmission line and a microwave power adaptive regulation and
control system are all new designed. The high-power microwave
generator effectively meets the practical engineering application
requirements, and a permanent magnet is used in the high-power
microwave generator for the first time to provide a magnetic field.
At the same time, a coaxial circulator is used in the high-power
microwave generator for the first time to isolate microwave
reflected power, so that the structure of the high-power microwave
generator can be more compact, the size is substantially reduced,
and the conditions for combining with rock fracturing machinery are
further provided. The high-power microwave coaxial heater has
higher power capacity and larger microwave radiation range, so that
the high-power borehole fracturing requirement can be met
effectively, and breakdown sparking due to air ionization can be
effectively avoided. The high-power low-loss microwave coaxial
transmission line has higher power capacity, and the microwave
energy loss during remote transmission is small, so that the
high-power borehole fracturing requirement can be met effectively,
and on-site assembly and disassembly are convenient. The microwave
power adaptive regulation and control system achieves the adaptive
regulation and control of the microwave power, when the load
impedance of the rock changes dynamically, the real-time matching
requirement of impedance can be met, the stability of the microwave
equipment is effectively improved, the microwave reflected power is
reduced to the maximum extent, and application requirements of the
microwave-assisted rock fracturing technology in practical
engineering are effectively met.
[0009] The high-power microwave borehole fracturing device for an
engineering rock mass includes a high-power microwave generator, a
high-power microwave coaxial heater, a high-power low-loss
microwave coaxial transmission line, and a microwave power adaptive
regulation and control system; wherein the high-power microwave
generator is connected with the high-power microwave coaxial heater
through the microwave power adaptive regulation and control system
and the high-power low-loss microwave coaxial transmission line
sequentially; the high-power microwave coaxial heater is used for
radiating microwave energy to cause fracturing of rocks around a
borehole of the engineering rock mass; the microwave power adaptive
regulation and control system is used for performing real-time
impedance matching of a microwave power outputted by the high-power
microwave generator; and the high-power low-loss microwave coaxial
transmission line is used for transmitting impedance-matched
microwaves into the high-power microwave coaxial heater.
[0010] The high-power microwave generator includes a continuous
wave magnetron, a permanent magnet, a waveguide excitation chamber,
a coaxial circulator, a coaxial matching load, a coaxial coupling
converter, a waveguide coaxial converter, and an output waveguide;
wherein the permanent magnet is a circular ring structure, and the
permanent magnet is fixedly sleeved around an outer side of the
continuous wave magnetron to provide a magnetic field for the
continuous wave magnetron; the continuous wave magnetron is
connected with a power supply through a wire, a microwave emitting
head of the continuous wave magnetron is located in the waveguide
excitation chamber, DC electrical energy is converted into
microwave energy by the continuous wave magnetron, the microwave
energy generated by the continuous wave magnetron enters the
waveguide excitation chamber through the microwave emitting head,
and a guided mode is formed in the waveguide excitation chamber;
three end openings are formed in the coaxial circulator, and
defined as a first end opening, a second end opening and a third
end opening respectively; the waveguide excitation chamber is
connected with the first end opening of the coaxial circulator
through the coaxial coupling converter, and the microwave energy
generated by the continuous wave magnetron enters the coaxial
circulator after passing through the waveguide excitation chamber
and the coaxial coupling converter sequentially; the output
waveguide is connected with the second end opening of the coaxial
circulator through the waveguide coaxial converter, the microwave
energy in the coaxial circulator enters the output waveguide
through the waveguide coaxial converter, and the microwave energy
is converted from a coaxial output mode to a waveguide mode; the
output waveguide is a microwave output portion of the high-power
microwave generator; and the coaxial matching load is connected to
the third end opening of the coaxial circulator, and the coaxial
matching load is used for absorbing microwave reflected power
isolated by the coaxial circulator and protecting the coaxial
circulator and the continuous wave magnetron.
[0011] The high-power microwave coaxial heater includes a microwave
transmission inner conductor, a microwave transmission outer
conductor, a microwave input connector, a microwave short circuit
cap, and a conductor supporting cylinder; wherein the microwave
transmission inner conductor is a solid cylinder structure or a
hollow cylinder structure, the microwave transmission outer
conductor is a cylindrical structure, the microwave transmission
outer conductor is coaxially sleeved around an outer side of the
microwave transmission inner conductor, and the microwave
transmission inner conductor and the microwave transmission outer
conductor which are arranged in a coaxial sleeving state are
fixedly mounted between the microwave input connector and the
microwave short circuit cap; an annular space is formed among the
microwave transmission inner conductor, the microwave transmission
outer conductor, the microwave input connector and the microwave
short circuit cap, and the annular space is stuffed by the
conductor supporting cylinder which maintains a coaxial state
between the microwave transmission inner conductor and the
microwave transmission outer conductor; and a plurality of
microwave radiating openings for radiating microwave energy
outwards are formed in a cylinder wall of the microwave
transmission outer conductor, and an anti-breakdown dielectric
block is stuffed in each of the microwave radiating openings.
[0012] The conductor supporting cylinder and the anti-breakdown
dielectric blocks are both made of a wave-transmitting material;
the microwave transmission inner conductor, the microwave
transmission outer conductor, the microwave input connector and the
microwave short circuit cap are all made of a conductive metal
material; each of the microwave radiating openings is in the shape
of a curved slit, and a length of the curved slit of the microwave
radiating opening is equal to 2/3 of a circumference of the
microwave transmission outer conductor; the anti-breakdown
dielectric blocks are exactly the same as the microwave radiating
openings in shape and size, the microwave radiating openings are
distributed in an axial direction of the microwave transmission
outer conductor in an equidistant manner, and the adjacent
microwave radiating openings face oppositely; a distance between
the adjacent microwave radiating openings is 1/ {square root over
(.epsilon..sub.r)}, wherein .epsilon..sub.r is a relative
dielectric constant of the wave-transmitting material; and a
distance between the microwave radiating opening adjacent to the
microwave short circuit cap and the microwave short circuit cap is
1/2.lamda..sub.p, wherein .lamda..sub.p=.lamda. {square root over
(.epsilon..sub.r)}; wherein .lamda..sub.p is a phase wavelength,
.lamda. is a microwave wavelength, and .epsilon..sub.r is the
relative dielectric constant of the wave-transmitting material.
[0013] The high-power low-loss microwave coaxial transmission line
is a combined structure, and includes an input end coaxial line,
middle section coaxial lines and an output end coaxial line,
wherein the input end coaxial line is connected with the output end
coaxial line through a plurality of middle section coaxial lines
connected in series; the input end coaxial line includes an input
end inner conductor, an input end outer conductor, an input end
microwave input connector, an input end microwave output connector,
and an input end conductor supporting disk; wherein the input end
inner conductor is a solid cylinder structure or a hollow cylinder
structure, the input end outer conductor is a cylindrical
structure, and the input end outer conductor is coaxially sleeved
around an outer side of the input end inner conductor; the input
end microwave input connector is coaxially and fixedly connected to
a front end aperture of the input end outer conductor, the input
end conductor supporting disk is fixedly mounted between the input
end inner conductor and the input end microwave input connector,
and a coaxial state between the input end inner conductor and the
input end outer conductor is maintained through the input end
conductor supporting disk; and the input end microwave output
connector is coaxially and fixedly connected to a rear end aperture
of the input end outer conductor.
[0014] Each of the middle section coaxial lines includes a middle
section inner conductor, a middle section outer conductor, a middle
section microwave input connector, a middle section microwave
output connector, and a middle section conductor supporting disk;
wherein the middle section inner conductor is a solid cylinder
structure or a hollow cylinder structure, the middle section outer
conductor is a cylindrical structure, and the middle section outer
conductor is coaxially sleeved around an outer side of the middle
section inner conductor; the middle section microwave input
connector is coaxially and fixedly connected to a front end
aperture of the middle section outer conductor, the middle section
conductor supporting disk is fixedly mounted between the middle
section inner conductor and the middle section microwave input
connector, and a coaxial state between the middle section inner
conductor and the middle section outer conductor is maintained
through the middle section conductor supporting disk; the middle
section microwave output connector is coaxially and fixedly
connected to a rear end aperture of the middle section outer
conductor; and the middle section microwave input connector and the
input end microwave output connector are in coaxial threaded
connection and matching, or the middle section microwave input
connector and the middle section microwave output connector of the
adjacent middle section coaxial line are in coaxial threaded
connection and matching.
[0015] The output end coaxial line includes an output end inner
conductor, an output end outer conductor, an output end microwave
input connector, an output end microwave output connector, an
output end front conductor supporting disk, and an output end rear
conductor supporting disk; wherein the output end inner conductor
is a solid cylinder structure or a hollow cylinder structure, the
output end outer conductor is a cylindrical structure, and the
output end outer conductor is coaxially sleeved around an outer
side of the output end inner conductor; the output end microwave
input connector is coaxially and fixedly connected to a front end
aperture of the output end outer conductor, and the output end
front conductor supporting disk is fixedly mounted between the
output end inner conductor and the output end microwave input
connector; the output end microwave output connector is coaxially
and fixedly connected to a rear end aperture of the output end
outer conductor, and the output end rear conductor supporting disk
is fixedly mounted between the output end inner conductor and the
output end microwave output connector, and a coaxial state between
the output end inner conductor and the output end outer conductor
is maintained by the output end front conductor supporting disk and
the output end rear conductor supporting disk; and the output end
microwave input connector and the middle section microwave output
connector are in coaxial threaded connection and matching.
[0016] A dry cooling air inlet is formed in the input end microwave
input connector, a plurality of dry cooling air through holes are
formed in the middle section conductor supporting disk and the
output end front conductor supporting disk, and a plurality of dry
cooling air exhaust holes are formed in the output end microwave
output connector.
[0017] The input end inner conductor, the input end outer
conductor, the input end microwave input connector, the input end
microwave output connector, the middle section inner conductor, the
middle section outer conductor, the middle section microwave input
connector, the middle section microwave output connector, the
output end inner conductor, the output end outer conductor, the
output end microwave input connector, and the output end microwave
output connector are all made of a conductive metal material; and
the input end conductor supporting disk, the middle section
conductor supporting disk, the output end front conductor
supporting disk, and the output end rear conductor supporting disk
are all made of a wave-transmitting material.
[0018] The microwave power adaptive regulation and control system
includes an impedance matching regulator, a microwave power
controller, and a temperature sensor; wherein one end of the
impedance matching regulator is used for receiving the microwaves
outputted by the high-power microwave generator, and the microwave
incident power is recorded in the impedance matching regulator; the
other end of the impedance matching regulator is used for
outputting microwaves; the microwaves outputted by the impedance
matching regulator are transmitted to the high-power microwave
coaxial heater through the high-power low-loss microwave coaxial
transmission line, and then the rock mass is fractured by the
microwaves radiated from the high-power microwave coaxial heater;
after the microwaves reflected by the rock mass return to the
impedance matching regulator after passing through the high-power
microwave coaxial heater and the high-power low-loss microwave
coaxial transmission line sequentially, the microwave reflected
power is recorded by the impedance matching regulator; the
microwave power controller is used for receiving the microwave
incident power and the microwave reflected power fed back by the
impedance matching regulator; the temperature sensor is used for
collecting temperature data of the rock mass during microwave
fracturing, and the temperature data is directly fed back to the
microwave power controller; reflection coefficient data of the rock
mass is pre-set in the microwave power controller; the microwave
power controller firstly takes the microwave incident power and the
microwave reflected power fed back by the impedance matching
regulator as the basis, and then calculates microwave power data
satisfying impedance matching through the temperature data and the
reflection coefficient data; and the microwave power controller
finally feeds back the microwave power data satisfying impedance
matching to the impedance matching regulator, and finally the
real-time impedance matching is performed on the microwave power
outputted by the high-power microwave generator through the
impedance matching regulator.
[0019] The high-power microwave borehole fracturing device for an
engineering rock mass has the beneficial effects that
[0020] a high-power microwave generator, a high-power microwave
coaxial heater, a high-power low-loss microwave coaxial
transmission line, and a microwave power adaptive regulation and
control system are all new designed therein. The high-power
microwave generator effectively meets the practical engineering
application requirements, and a permanent magnet is used in the
high-power microwave generator for the first time to provide a
magnetic field. At the same time, a coaxial circulator is used in
the high-power microwave generator for the first time to isolate
microwave reflected power, so that the structure of the high-power
microwave generator can be more compact, the size is substantially
reduced, and the conditions for combining with rock fracturing
machinery are further provided. The high-power microwave coaxial
heater has higher power capacity and larger microwave radiation
range, so that the high-power borehole fracturing requirement can
be met effectively, and breakdown sparking due to air ionization
can be effectively avoided. The high-power low-loss microwave
coaxial transmission line has higher power capacity, and the
microwave energy loss during remote transmission is small, so that
the high-power borehole fracturing requirement can be met
effectively, and on-site assembly and disassembly are convenient.
The microwave power adaptive regulation and control system achieves
the adaptive regulation and control of the microwave power, when
the load impedance of the rock changes dynamically, the real-time
matching requirement of impedance can be met, the stability of the
microwave equipment is effectively improved, the microwave
reflected power is reduced to the maximum extent, and application
requirements of the microwave-assisted rock fracturing technology
in practical engineering are effectively met.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic structural diagram of a high-power
microwave borehole fracturing device for an engineering rock mass
of the present invention;
[0022] FIG. 2 is a schematic structural diagram of a high-power
microwave generator of the present invention;
[0023] FIG. 3 is a work flow diagram of the high-power microwave
generator of the present invention;
[0024] FIG. 4 is a schematic structural diagram of a high-power
microwave coaxial heater of the present invention;
[0025] FIG. 5 is a cross-sectional view taken along line A-A of
FIG. 4;
[0026] FIG. 6 is a cross-sectional view taken along line B-B of
FIG. 4;
[0027] FIG. 7 is a work state diagram of the high-power microwave
coaxial heater of the present invention;
[0028] FIG. 8 is a schematic structural diagram of a high-power
low-loss microwave coaxial transmission line of the present
invention;
[0029] FIG. 9 is a schematic structural diagram of an input end
coaxial line;
[0030] FIG. 10 is a schematic structural diagram of a middle
section coaxial line;
[0031] FIG. 11 is a schematic structural diagram of an output end
coaxial line;
[0032] FIG. 12 is a structure block diagram of a microwave power
adaptive regulation and control system of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033] The present invention is described in details below with
reference to the accompanying figures and specific embodiments.
[0034] As shown in FIGS. 1-12, a high-power microwave borehole
fracturing device for an engineering rock mass includes a
high-power microwave generator 1, a high-power microwave coaxial
heater 2, a high-power low-loss microwave coaxial transmission line
3, and a microwave power adaptive regulation and control system 4.
The high-power microwave generator 1 is connected with the
high-power microwave coaxial heater 2 through the microwave power
adaptive regulation and control system 4 and the high-power
low-loss microwave coaxial transmission line 3 sequentially. The
high-power microwave coaxial heater 2 is used for radiating
microwave energy to cause fracturing of rocks around a borehole of
the engineering rock mass. The microwave power adaptive regulation
and control system 4 is used for performing real-time impedance
matching of a microwave power outputted by the high-power microwave
generator 1. The high-power low-loss microwave coaxial transmission
line 3 is used for transmitting impedance-matched microwaves into
the high-power microwave coaxial heater 2.
[0035] The high-power microwave generator 1 includes a continuous
wave magnetron 11, a permanent magnet 12, a waveguide excitation
chamber 13, a coaxial circulator 14, a coaxial matching load 15, a
coaxial coupling converter 16, a waveguide coaxial converter 17,
and an output waveguide 18. The permanent magnet 12 is a circular
ring structure, and the permanent magnet 12 is fixedly sleeved
around an outer side of the continuous wave magnetron 11 to provide
a magnetic field for the continuous wave magnetron 11. The
continuous wave magnetron 11 is connected with a power supply
through a wire, a microwave emitting head of the continuous wave
magnetron 11 is located in the waveguide excitation chamber 13, DC
electrical energy is converted into microwave energy by the
continuous wave magnetron 11, the microwave energy generated by the
continuous wave magnetron 11 enters the waveguide excitation
chamber 13 through the microwave emitting head, and a guided mode
is formed in the waveguide excitation chamber 13. Three end
openings are formed in the coaxial circulator 14, and defined as a
first end opening, a second end opening and a third end opening
respectively. The waveguide excitation chamber 13 is connected with
the first end opening of the coaxial circulator 14 through the
coaxial coupling converter 16, and the microwave energy generated
by the continuous wave magnetron 11 enters the coaxial circulator
14 after passing through the waveguide excitation chamber 13 and
the coaxial coupling converter 16 sequentially. The output
waveguide 18 is connected with the second end opening of the
coaxial circulator 14 through the waveguide coaxial converter 17,
the microwave energy in the coaxial circulator 14 enters the output
waveguide 18 through the waveguide coaxial converter 17, and the
microwave energy is converted from a coaxial output mode to a
waveguide mode. The output waveguide 18 is a microwave output
portion of the high-power microwave generator 1. The coaxial
matching load 15 is connected to the third end opening of the
coaxial circulator 14, and the coaxial matching load 15 is used for
absorbing microwave reflected power isolated by the coaxial
circulator 14 and protecting the coaxial circulator 14 and the
continuous wave magnetron 11.
[0036] After the power supply of the continuous wave magnetron 11
is connected, the continuous wave magnetron 11 converts the DC
electrical energy into microwave energy under the action of the
magnetic field provided by the permanent magnet 12. The microwave
energy firstly enters the waveguide excitation chamber 13 and forms
the guided mode in the waveguide excitation chamber 13, and then
enters the coaxial circulator 14 through the coaxial coupling
converter 16. The microwave energy entering the coaxial circulator
14 can enter the output waveguide 18 through the waveguide coaxial
converter 17. In the process, the microwave energy converts from
the coaxial output mode to the waveguide mode. Finally, the
microwave energy in the waveguide mode is directly outputted by the
output waveguide 18 and transmitted to the high-power microwave
coaxial heater 2 at the terminal through the high-power low-loss
microwave coaxial transmission line 3.
[0037] After the high-power microwave coaxial heater 2 generates
the microwave reflected power, the microwave reflected power enters
the coaxial matching load 15 after passing through the high-power
low-loss microwave coaxial transmission line 3, the output
waveguide 18, the waveguide coaxial converter 17 and the coaxial
circulator 14 sequentially, and the microwave reflected power
isolated by the coaxial circulator 14 is absorbed by the coaxial
matching load 15 for protecting the coaxial circulator 14 and the
continuous wave magnetron 11.
[0038] The high-power microwave coaxial heater 2 includes a
microwave transmission inner conductor 21, a microwave transmission
outer conductor 22, a microwave input connector 23, a microwave
short circuit cap 24, and a conductor supporting cylinder 25. The
microwave transmission inner conductor 21 is a solid cylinder
structure or a hollow cylinder structure, the microwave
transmission outer conductor 22 is a cylindrical structure, the
microwave transmission outer conductor 22 is coaxially sleeved
around an outer side of the microwave transmission inner conductor
21, and the microwave transmission inner conductor 21 and the
microwave transmission outer conductor 22 which are arranged in a
coaxial sleeving state are fixedly mounted between the microwave
input connector 23 and the microwave short circuit cap 24. An
annular space is formed among the microwave transmission inner
conductor 21, the microwave transmission outer conductor 22, the
microwave input connector 23 and the microwave short circuit cap
24, and the annular space is stuffed by the conductor supporting
cylinder 25 which maintains a coaxial state between the microwave
transmission inner conductor 21 and the microwave transmission
outer conductor 22. A plurality of microwave radiating openings 26
for radiating microwave energy outwards are formed in a cylinder
wall of the microwave transmission outer conductor 22, and an
anti-breakdown dielectric block 27 is stuffed in each of the
microwave radiating openings 26.
[0039] The conductor supporting cylinder 25 and the anti-breakdown
dielectric blocks 27 are both made of a wave-transmitting material.
In the embodiment, polytetrafluoroethylene is selected as the
wave-transmitting material. The microwave transmission inner
conductor 21, the microwave transmission outer conductor 22, the
microwave input connector 23 and the microwave short circuit cap 24
are all made of a conductive metal material. In the embodiment,
copper is selected as the conductive metal material. Each of the
microwave radiating openings 26 is in the shape of a curved slit,
and a length of the curved slit of the microwave radiating opening
26 is equal to 2/3 of a circumference of the microwave transmission
outer conductor 22. Due to the arrangement of the microwave
radiating openings 26 in the shape of the curved slit, current
lines of an inner wall of the microwave transmission outer
conductor 22 are cut, and further the microwave radiating openings
26 are excited to radiate microwave energy outwards. The
anti-breakdown dielectric blocks 27 are exactly the same as the
microwave radiating openings 26 in shape and size, the microwave
radiating openings 26 are distributed in an axial direction of the
microwave transmission outer conductor 22 in an equidistant manner,
and the adjacent microwave radiating openings 26 face oppositely. A
distance between the adjacent microwave radiating openings 26 is 1/
{square root over (.epsilon..sub.r )}, wherein .epsilon..sub.r is a
relative dielectric constant of the wave-transmitting material.
Since the conductor supporting cylinder 25 made of the
wave-transmitting material is stuffed between the microwave
transmission inner conductor 21 and the microwave transmission
outer conductor 22, the distance between the adjacent microwave
radiating openings 26 can be only 1/ {square root over
(.epsilon..sub.r)}, and the number of microwave radiating openings
26 on the microwave transmission outer conductor 22 with a limited
length is effectively increased, so that not only can the heating
uniformity of the microwave radiation be guaranteed, but also a
power capacity of the high-power microwave coaxial heater 2 is
greatly increased. A distance between the microwave radiating
opening 26 adjacent to the microwave short circuit cap 24 and the
microwave short circuit cap 24 is 1/2.lamda., wherein
.lamda..sub.p=.lamda. {square root over (.epsilon..sub.r)}; wherein
.lamda..sub.p is a phase wavelength, .lamda. is a microwave
wavelength, and .epsilon..sub.r is the relative dielectric constant
of the wave-transmitting material. Therefore, a position of each
microwave radiating opening 26 is guaranteed to be a wave peak of
one of the microwaves, namely that each microwave radiating opening
26 can be excited to the maximum extent.
[0040] After the high-power low-loss microwave coaxial transmission
line 3 is connected with the microwave input connector 23, the
high-power microwave coaxial heater 2 can extend into the borehole
of the rock mass. The microwave energy can enter the high-power
microwave coaxial heater 2 through the high-power low-loss
microwave coaxial transmission line 3, and firstly enters the
annular space between the microwave transmission inner conductor 21
and the microwave transmission outer conductor 22. The current
lines of the inner wall of the microwave transmission outer
conductor 22 are cut by the microwave radiating openings 26 in the
shape of the curved slit, so that the microwave radiating openings
26 can be excited to radiate microwave energy outwards. The
radiated microwave energy is directly absorbed by the rocks around
the borehole of the rock mass, so that the rocks around the
borehole of the rock mass can be fractured.
[0041] When the microwave radiating openings 26 are used for
high-power borehole microwave fracturing, due to the anti-breakdown
dielectric blocks 27 made of the wave-transmitting material, a gap
between the microwave radiating openings 26 can be prevented from
being broken down even if the radiation field strength of the
microwave radiating openings 26 is very high. In the embodiment,
polytetrafluoroethylene is selected as the wave-transmitting
material, of which the breakdown field strength can be up to 200
kV/mm, while the breakdown field strength of an air medium is only
30 kV/mm.
[0042] The high-power low-loss microwave coaxial transmission line
3 is a combined structure, and includes an input end coaxial line
31, middle section coaxial lines 32 and an output end coaxial line
33. The input end coaxial line 31 is connected with the output end
coaxial line 33 through a plurality of middle section coaxial lines
32 connected in series.
[0043] The input end coaxial line 31 includes an input end inner
conductor 34, an input end outer conductor 35, an input end
microwave input connector 36, an input end microwave output
connector 37, and an input end conductor supporting disk 38. The
input end inner conductor 34 is a solid cylinder structure or a
hollow cylinder structure, the input end outer conductor 35 is a
cylindrical structure, and the input end outer conductor 35 is
coaxially sleeved around an outer side of the input end inner
conductor 34. The input end microwave input connector 36 is
coaxially and fixedly connected to a front end aperture of the
input end outer conductor 35, the input end conductor supporting
disk 38 is fixedly mounted between the input end inner conductor 34
and the input end microwave input connector 36, and a coaxial state
between the input end inner conductor 34 and the input end outer
conductor 35 is maintained through the input end conductor
supporting disk 38. The input end microwave output connector 37 is
coaxially and fixedly connected to a rear end aperture of the input
end outer conductor 35.
[0044] Each of the middle section coaxial lines 32 includes a
middle section inner conductor 39, a middle section outer conductor
310, a middle section microwave input connector 311, a middle
section microwave output connector 312, and a middle section
conductor supporting disk 313. The middle section inner conductor
39 is a solid cylinder structure or a hollow cylinder structure,
the middle section outer conductor 310 is a cylindrical structure,
and the middle section outer conductor 310 is coaxially sleeved
around an outer side of the middle section inner conductor 39. The
middle section microwave input connector 311 is coaxially and
fixedly connected to a front end aperture of the middle section
outer conductor 310, the middle section conductor supporting disk
313 is fixedly mounted between the middle section inner conductor
39 and the middle section microwave input connector 311, and a
coaxial state between the middle section inner conductor 39 and the
middle section outer conductor 310 is maintained through the middle
section conductor supporting disk 313. The middle section microwave
output connector 312 is coaxially and fixedly connected to a rear
end aperture of the middle section outer conductor 310. The middle
section microwave input connector 311 and the input end microwave
output connector 37 are in coaxial threaded connection and
matching, or the middle section microwave input connector 311 and
the middle section microwave output connector 312 of the adjacent
middle section coaxial line 32 are in coaxial threaded connection
and matching.
[0045] The output end coaxial line 33 includes an output end inner
conductor 314, an output end outer conductor 315, an output end
microwave input connector 316, an output end microwave output
connector 317, an output end front conductor supporting disk 318,
and an output end rear conductor supporting disk 319. The output
end inner conductor 314 is a solid cylinder structure or a hollow
cylinder structure, the output end outer conductor 315 is a
cylindrical structure, and the output end outer conductor 315 is
coaxially sleeved around an outer side of the output end inner
conductor 314. The output end microwave input connector 316 is
coaxially and fixedly connected to a front end aperture of the
output end outer conductor 315, and the output end front conductor
supporting disk 318 is fixedly mounted between the output end inner
conductor 314 and the output end microwave input connector 316. The
output end microwave output connector 317 is coaxially and fixedly
connected to a rear end aperture of the output end outer conductor
315, and the output end rear conductor supporting disk 319 is
fixedly mounted between the output end inner conductor 314 and the
output end microwave output connector 317, and a coaxial state
between the output end inner conductor 314 and the output end outer
conductor 315 is maintained by the output end front conductor
supporting disk 318 and the output end rear conductor supporting
disk 319. The output end microwave input connector 316 and the
middle section microwave output connector 312 are in coaxial
threaded connection and matching.
[0046] A dry cooling air inlet 320 is formed in the input end
microwave input connector 36, a plurality of dry cooling air
through holes 321 are formed in the middle section conductor
supporting disk 313 and the output end front conductor supporting
disk 318, and a plurality of dry cooling air exhaust holes 322 are
formed in the output end microwave output connector 317.
[0047] The input end inner conductor 34, the input end outer
conductor 35, the input end microwave input connector 36, the input
end microwave output connector 37, the middle section inner
conductor 39, the middle section outer conductor 310, the middle
section microwave input connector 311, the middle section microwave
output connector 312, the output end inner conductor 314, the
output end outer conductor 315, the output end microwave input
connector 316, and the output end microwave output connector 317
are all made of a conductive metal material. In the embodiment,
copper is selected as the conductive metal material.
[0048] The input end conductor supporting disk 38, the middle
section conductor supporting disk 313, the output end front
conductor supporting disk 318, and the output end rear conductor
supporting disk 319 are all made of a wave-transmitting material.
In the embodiment, polytetrafluoroethylene is selected as the
wave-transmitting material.
[0049] In order to further increase the electrical conductivity
between the outer conductors and the inner conductors to further
reduce the transmission loss, a layer of low-resistivity material
can be coated onto the inner surfaces of the outer conductors and
the outer surfaces of the inner conductors.
[0050] Because the input end coaxial line 31 and one of the middle
section coaxial lines 32, the adjacent middle section coaxial lines
32, and one of the middle section coaxial lines 32 and the output
end coaxial line 33 are in threaded connection, good electrical
contact between the outer conductors and the inner conductors is
guaranteed, and excessive energy loss due to poor electrical
contact is avoided; and besides, the threaded connection manner is
more convenient for disassembly and assembly of the microwave
coaxial transmission line 3 on site.
[0051] In order to prevent the microwave coaxial transmission line
3 from generating high heat while transmitting high-power
microwaves, the microwave coaxial transmission line 3 is cooled in
real time by dry cooling air 323 to prevent high temperature from
adversely affecting the transmission characteristics of the air
medium.
[0052] Before the high-power low-loss microwave coaxial
transmission line 3 is used, the input end coaxial line 31, the
middle section coaxial lines 32 and the output end coaxial line 33
in a dispersed state need to be assembled together in series, and
the assembled high-power low-loss microwave coaxial transmission
line 3 is connected between the microwave power adaptive regulation
and control system 4 and the high-power microwave coaxial heater 2.
Before microwave fracturing is performed, the dry cooling air inlet
320 needs to communicate with an air outlet of a dry cooler (not
shown).
[0053] When microwave fracturing is performed, the dry cooler needs
to be started. The high-power microwave firstly enters the input
end coaxial line 31, and then is transmitted to the high-power
microwave coaxial heater 2 after passing through the middle section
coaxial lines 32 and the output end coaxial line 33 sequentially.
Finally, the microwave energy is radiated outwards through the
high-power microwave coaxial heater 2, and the radiated microwave
energy is directly absorbed by the rocks around the borehole of the
rock mass, so that the rocks around the borehole of the rock mass
can be fractured.
[0054] In the process of high-power microwave transmission, the dry
cooling air 323 outputted by the dry cooler passes through the
input end coaxial line 31, the middle section coaxial lines 32 and
the output end coaxial line 33 sequentially, until being exhausted
from the dry cooling air exhaust holes 322. The microwave coaxial
transmission line is cooled in real time by the dry cooling air 323
to prevent the high temperature from adversely affecting the
transmission characteristics of the air medium.
[0055] The microwave power adaptive regulation and control system 4
includes an impedance matching regulator, a microwave power
controller, and a temperature sensor. One end of the impedance
matching regulator is used for receiving the microwaves outputted
by the high-power microwave generator 1, and the microwave incident
power is recorded in the impedance matching regulator. The other
end of the impedance matching regulator is used for outputting
microwaves The microwaves outputted by the impedance matching
regulator are transmitted to the high-power microwave coaxial
heater 2 through the high-power low-loss microwave coaxial
transmission line 3, and then the rock mass is fractured by the
microwaves radiated from the high-power microwave coaxial heater 2.
After the microwaves reflected by the rock mass return to the
impedance matching regulator after passing through the high-power
microwave coaxial heater 2 and the high-power low-loss microwave
coaxial transmission line 3 sequentially, the microwave reflected
power is recorded by the impedance matching regulator, and the
microwave power controller is used for receiving the microwave
incident power and the microwave reflected power fed back by the
impedance matching regulator. The temperature sensor is used for
collecting temperature data of the rock mass during microwave
fracturing, and the temperature data is directly fed back to the
microwave power controller. Reflection coefficient data of the rock
mass is pre-set in the microwave power controller. The microwave
power controller firstly takes the microwave incident power and the
microwave reflected power fed back by the impedance matching
regulator as the basis, and then calculates microwave power data
satisfying impedance matching through the temperature data and the
reflection coefficient data. And the microwave power controller
finally feeds back the microwave power data satisfying impedance
matching to the impedance matching regulator, and finally the
real-time impedance matching is performed on the microwave power
outputted by the high-power microwave generator 1 through the
impedance matching regulator.
[0056] A microwave power adaptive regulation and control method
includes the steps of: starting the high-power microwave generator
1, inputting microwaves into the impedance matching regulator
through the high-power microwave generator 1, and performing
initial matching regulation on the input microwave power through
the impedance matching regulator; after the microwave power is
regulated through initial matching, transmitting the microwaves
outputted by the impedance matching regulator to the high-power
microwave coaxial heater 2 through the high-power low-loss
microwave coaxial transmission line 3, and then enabling the rock
mass to be fractured by the microwaves radiated from the high-power
microwave coaxial heater 2, wherein Some of the microwave energy
can be absorbed by the rock mass, and some of the microwave energy
is reflected back into the impedance matching regulator through the
high-power microwave coaxial heater 2 and the high-power low-loss
microwave coaxial transmission line 3 sequentially, and the
microwave incident power and the microwave reflected power are
recorded by the impedance matching regulator; feeding the
temperature data of the rock mass collected by the temperature
sensor during microwave fracturing to the microwave power
controller, wherein the microwave power controller takes the
microwave incident power and the microwave reflected power fed back
by the impedance matching regulator as the basis, and then
calculating the microwave power data satisfying impedance matching
through the temperature data and the reflection coefficient data;
and feeding back the microwave power data satisfying impedance
matching to the impedance matching regulator through the microwave
power controller, and performing real-time impedance matching on
the microwave power outputted by the high-power microwave generator
1 through the impedance matching regulator.
[0057] In the embodiment, the microwave power controller is a
programmable logic controller (PLC), and a power regulation model
is established in the PLC by a proportional integral differential
(PID) algorithm. The PLC drives the impedance matching regulator
through the power regulation model to establish a mathematical
model or a data sheet, for quickly forming microwave power control
information in the PLC, so that the impedance matching regulator
can quickly achieve impedance matching. The microwave power
regulated through impedance matching is then radiated to the rock
mass by the high-power microwave coaxial heater 2 for fracturing,
so that the microwave reflected power can be reduced to the
minimum.
[0058] In the embodiment, in order to obtain the pre-set reflection
coefficient data of the rock mass, an effective dielectric constant
of the rock mass needs to be measured in advance and characterized
by using a binomial expansion, and then the obtained
characterization formula of the effective dielectric constant is
substituted into a model of the high-power microwave coaxial heater
2 for simulation calculation, so that corresponding relation
between the reflection coefficient and the effective dielectric
constant of the rock mass can be obtained. Since the reflection
coefficient is determined by the effective dielectric constant of
the rock mass, the reflection coefficient and the effective
dielectric constant of the rock mass form one-to-one corresponding
relation, and the effective dielectric constant of the rock mass
and the temperature data of the rock mass also form a one-to-one
corresponding relation. Therefore, the microwave power data
satisfying impedance matching can be calculated through the
reflection coefficient and the temperature data.
[0059] The scheme in the embodiment is not intended to limit the
scope of patent protection of the present invention. Any equivalent
implementation or modification without departing from the present
invention should be included in the scope of patent of the present
invention.
* * * * *